Final answer:
When parking uphill, wheels should be turned away from the curb to prevent the vehicle from rolling into traffic, employing static friction and a physical barrier for safety. This is an application of Newton's first law, where static friction force helps maintain the vehicle at rest.
Step-by-step explanation:
When parking a vehicle facing uphill, the correct procedure is to turn the wheels away from the curb. This ensures that if the vehicle starts to roll, it will move away from the street and towards the curb, serving as a block to stop the car from rolling into traffic. This advice assumes there is a curb; if there is no curb, the correct procedure may differ.
The principle behind this practice ties into physics and the concept of static friction, although in this instance, it's a practical application for safety rather than a physical calculation of forces. The static friction force between the tires and the road surface is what helps prevent the vehicle from rolling downhill. Should the vehicle start moving, the curb acts as a physical barrier.
Referring back to the original question about the truck parked at the top of a hill, if it runs freely down the hill, it is an illustration of the principles of motion, specifically Newton's first law. This law states that an object will remain at rest or move at a constant velocity unless acted upon by an external force, highlighting the importance of correctly parking with wheels turned appropriately to avoid such a situation.